In general, a semiconductor manufacturing apparatus includes a crystal growth equipment, such as a metal organic chemical vapor deposition (MOCVD) apparatus, a molecular beam epitaxy (MBE) apparatus, and a chemical vapor deposition (CVD) apparatus. Such a crystal growth equipment is used for growing an element, such as a semiconductor light emitting device, a high electron mobility transistor (HEMT), a field effect transistor (FET), and a laser diode on the surface of a wafer.
A susceptor of vacuous type is commonly used as an apparatus for loading a wafer in the crystal growth equipment.
FIG. 1 schematically illustrates a related art semiconductor manufacturing apparatus. Referring to FIGS. 1 and 2, a semiconductor manufacturing apparatus 10 includes a reaction chamber 20, a susceptor 30, a rotation shaft 50, a heater 60, and a shroud 70. A plurality of pockets 34 are formed in the top surface of the susceptor 30 in the reaction chamber 20 and a wafer 40 is loaded on each of the pockets 34. Here, as illustrated in FIG. 2B, the bottom surface 38 of the pocket 34 has a horizontal structure. The rotation shaft 50 is coupled with the under part of the susceptor 30 and the heater 60 is provided under the susceptor 30 to heat the under part of the susceptor 30. The shroud 70 on the reaction chamber 20 supplies source materials to the reaction chamber 20.
Processes of manufacturing a semiconductor using the semiconductor manufacturing apparatus are as follows.
The wafer 40 is loaded on the pocket 34 of the susceptor 30. The source materials are supplied to the reaction chamber 20 through the shroud 70. The susceptor 30 rotates by the rotation shaft 50. The susceptor 30 and the inside of the reaction chamber 20 are heated by the heater 60. At this time, a semiconductor thin film or an insulating layer is formed on the surface of the wafer 40 by the chemical reaction of the flowed source materials.
At this time, an aluminum nitride layer, a gallium nitride layer, and an indium nitride layer or an aluminum-gallium nitride layer, an aluminum-indium nitride layer, and a gallium-indium nitride layer can be deposited on the surface of the wafer 40 loaded on the susceptor 30 by a vapor reaction between organic metal and ammonia.
The heat generated by the heater 60 heats a region having the same radius based on the rotation shaft 50 of the susceptor 30 at a uniform temperature but cannot heat a region having a different radius at the uniform temperature. Therefore, since the rotation shaft 50 positioned in the center of the susceptor 30 transfers the heat in the center of the susceptor 30, a difference in temperature is generated between the center region and the outer region of the susceptor 30. Temperature is reduced from the center point of the pocket toward the inner point of the pocket as illustrated in the before modification susceptor graph of FIG. 9.
As a result, a difference in temperature is generated on the surface of the wafer loaded on the susceptor 30. Therefore, the outer region and the inner region of the epitaxial layer deposited on the wafer have different growth speeds. Accordingly, emission wavelength deviation is generated in the semiconductor light emitting devices produced in one wafer and the thicknesses of a material layer grown in one wafer vary a lot in accordance with regions.
As described above, the ranges of the emission wavelengths of the semiconductor devices produced on one susceptor or one wafer are not uniform but are various.